The present invention relates to the field of capacitive sensing, for example methods and apparatus employing capacitive sensors as user interfaces for receiving user inputs for controlling an operating function of an apparatus.
FIG. 1 schematically represents components of a conventional apparatus 100 employing a capacitive touch panel for receiving user inputs to control an operating function of the apparatus. In this regard the apparatus 100 may be considered to comprise a host component 102 and a touch panel module 104.
The host component 102 comprises a host controller 110 for controlling operating functions of the apparatus 100, which are schematically indicated in FIG. 1 by the element labelled “host functionality” 114. The nature of the host functionality 114 is not significant to the principles described herein and will depend on the application at hand. The host component 102 further comprises a power supply 112, which in this example is configured to provide DC power to the host controller 110 and the touch panel module 104 via a power bus comprising an apparatus ground potential line (schematically shown in FIG. 1 by a dashed line) and an apparatus power (+V) line (schematically shown in FIG. 1 by a solid line), as indicated in the legend and the top of the figure. Although not specifically shown in FIG. 1, it will be appreciated the power supply 112 will generally also supply power to other aspects of the apparatus, for example associated with its functionality 114.
The touch panel module 104 comprises a touch panel sensor element (touch screen) 122 and a touch panel controller 120. The touch panel sensor element 122 comprises a sensor surface (i.e. a surface within which the presence of an adjacent object, such as a user's finger, is to be detected) defined by an array of electrodes arranged on a substrate. The sensor controller 120 is configured to measure capacitance characteristics associated with the array of electrodes defining the sensor element 122 and to process these capacitance measurements to determine the presence and/or location of an object adjacent the sensor element 122. These aspects of capacitive sensor operations are well established and understood. The sensor controller 120 is further configured to provide an indication of the measurements to the host controller 110 over a touch panel output channel (communications link) 118 so the host controller 110 can respond accordingly. The communications link 118 may be bidirectional in that it may also be used for the host controller 110 to communicate configuration information to the touch panel module.
Capacitive sensor based user interfaces have become commonplace and well-established in many areas, for example ranging from mobile phones, computers, tablets, domestic goods, automobiles and so on. Capacitive sensor based user inputs are often perceived to be more aesthetically pleasing and are in many respects more robust than other user input mechanisms, for example based on mechanical buttons, which may be more prone to wear. Capacitive sensor based user interfaces also provide for enhanced flexibility, for example allowing ready reconfiguration of the user interface, for examples to suit different operating modes in a particular apparatus or different operating functionality among different apparatus. It can therefore be expected for capacitive sensor based user interfaces to become more and more prevalent, and in this regard there is an ongoing desire to provide capacitive sensor based user interfaces with further enhanced functionality.